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How is pitch related to the frequency of a sound wave?

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Diagram showing auditory mechanisms in insects, including labeled illustrations of a scolophore organ, the mosquito ear with antenna shaft and scolophores, the cicada ear with auditory capsule and tympanic membrane, and the grasshopper ear with sensory body and tympanic membrane. — sound reception Auditory mechanisms in insects. (Left) A scolophore organ. (Top right) The mosquito ear. (Centre right) The ear of the cicada *Magicicada septendecim*. (Bottom right) The ear of the grasshopper.

In the context of biology and sound reception, pitch is the physiological perception of the physical property known as frequency. Frequency refers to the number of sound wave cycles—or wavelengths—that pass a specific point per second, typically measured in hertz.1

The relationship is direct: the higher the frequency of a sound wave, the higher the perceived pitch.1

Within the human ear, this relationship is processed through the cochlea, which acts as a frequency analyzer. Different frequencies cause vibrations at specific locations along the basilar membrane:2
* High-frequency sounds cause the basal end of the membrane to vibrate.2
* Low-frequency sounds cause the apical end of the membrane to vibrate.2

The brain identifies the pitch by recognizing which specific group of nerve fibres is activated by the vibration at these different locations. For lower frequencies (up to approximately 3,000 hertz), the rate of nerve stimulation also serves as a critical indicator of pitch to the brain.2